Instance volume limits

The maximum number of Amazon EBS volumes that you can attach to an instance depends on the instance type and instance size. When considering how many volumes to attach to your instance, you should consider whether you need increased I/O bandwidth or increased storage capacity.

Bandwidth versus capacity

For consistent and predictable bandwidth use cases, use Amazon EBS–optimized instances with General Purpose SSD volumes or Provisioned IOPS SSD volumes. For maximum performance, match the IOPS you have provisioned for your volumes with the bandwidth available for your instance type.

For RAID configurations, you might find that arrays larger than 8 volumes have diminished performance returns due to increased I/O overhead. Test your individual application performance and tune it as required.

Volume limits for instances built on the Nitro System

Dedicated Amazon EBS volume limit

The following Nitro instance types have a dedicated Amazon EBS volume limit of up to 128 attachments, depending on instance size. The limit is not shared with other device attachments. In other words, you can attach any number of Amazon EBS volumes up to the volume attachment limit, regardless of the number of attached devices, such as NVMe instance store volumes and network interfaces.

• General purpose: M7a, M7i

• Compute optimized: C7a, C7i

• Memory optimized: R7a, R7i, R7iz

The volume limits depend on the instance size. The following table shows the limit for each instance size.

Instance size	Volume limit
medium | large | xlarge | 2xlarge | 4xlarge | 8xlarge | 12xlarge	32
16xlarge	48
24xlarge	64
32xlarge	88
48xlarge	128
metal-16xl | metal-24xl	31
metal-32xl | metal-48xl	79

Shared Amazon EBS volume limit

All other Nitro instance types have a volume attachment limit that is shared between Amazon EBS volumes, network interfaces, and NVMe instance store volumes. You can attach any number of Amazon EBS volumes up to that limit, less the number of attached network interfaces and NVMe instance store volumes. Keep in mind that every instance must have at least one network interface, and that NVMe instance store volumes are automatically attached at launch.

Most of these instances support a maximum of 28 attachments. For example, if you have no additional network interface attachments on an m5.xlarge instance, you can attach up to 27 EBS volumes (28 volume limit - 1 network interface). If you have two additional network interfaces on an m5.xlarge instance, you can attach up to 25 EBS volumes (28 volume limit - 3 network interfaces). Similarly, if you have two additional network interfaces on an m5d.xlarge instance, which has 1 NVMe instance store volume, you can attach up to 24 EBS volumes (28 volume limit - 3 network interfaces - 1 NVMe instance store volume).

The following exceptions apply:

• DL2q instances support a maximum of 19 EBS volumes.

• Most bare metal instances support a maximum of 31 EBS volumes.

• High memory virtualized instances support a maximum of 27 EBS volumes.

• High memory bare metal instances support a maximum of 19 EBS volumes.

• inf1.xlarge and inf1.2xlarge instances support a maximum of 26 EBS volumes.

• inf1.6xlarge instances support a maximum of 23 EBS volumes.

• mac1.metal instances support a maximum of 16 EBS volumes.

• inf1.24xlarge instances support a maximum of 11 EBS volumes.

• g5.48xlarge instances support a maximum of 9 EBS volumes.

• d3.8xlarge and d3en.12xlarge instances support a maximum of 3 EBS volumes.

• For accelerated computing instances, the attached accelerators count towards the shared volume limit. For example, for p4d.24xlarge instances, which have a shared volume limit of 28, 8 GPUs, and 8 NVMe instance store volumes, you can attach up to 11 Amazon EBS volumes (28 volume limit - 1 network interface - 8 GPUs - 8 NVMe instance store volumes).

Volume limits for Xen-based instances

Attaching more than 40 volumes to a Xen-based Linux instance can cause boot failures. This number includes the root volume, plus any attached instance store volumes and Amazon EBS volumes.

If you experience boot problems on an instance with a large number of volumes, stop the instance, detach any volumes that are not essential to the boot process, start the instance, and then reattach the volumes after the instance is running.

Important

Attaching more than 40 volumes to a Xen-based Linux instance is supported on a best effort basis only and is not guaranteed.